Hornady Sub-X 338 307gr Reloading Bullets - 50 Rounds - SubX (Subsonic - eXpanding) bullets deliver big results without a big bang! Designed to provide deep penetration below the speed of sound, SubX features a lead core. Long grooves in its gilding metal jacket combine with its flat profile and the patented Flex Tip insert within the bullet's hollowpoint cavity to help it expand reliably at low velocities. Cannelures provide positive case crimp, making SubX ideal for semiautomatic firearms. Features Made in the USA ; EXPANDS AT SUBSONIC VELOCITIES: Patented Flex Tip technology aids in expansion at velocities as low as 900 fps; PROVEN PERFORMANCE: Meets FBI protocol for terminal ballistic test requirements; POSITIVE CASE CRIMP: Lead core bullet with cannelured jacket provides positive case crimp for use in semiautomatics; WIDE RANGE OF GUNS: Designed to fit, feed and function in a variety of firearms, including gas system guns;